Power operated pressing machines



A18- 4, 1959 T. B. WALKER ETAL 2,897,652 POWER`OPERATD PRESSING MACHINES y Filed Sept. 17, 1956 3 Sheets-Sheet 1 BY MKM ATTORNEY` Aug. 4, 1959 r. awALkER Erm.

POWER OPERATED PRESSING MACHINES 5 Sheets-Sheet 2 Fild sept. 17, 1956 3 Sheets-Sheet 3 Aug. 4, 1959 Filed Sept. 17, 1956 2,897,652 Patented Aug. 4, 1959 United y States! APatent Offre@ 2,897,652 POWER OPERATED PRESSING MACHINES Thomas Bradley Walker and Robert Ernest English, Kendal, England, assignors to Isaac Braithwaite & Son Engineers Limited, Kendal, England, a corporation of Great Britain Application September 17, 1956, Serial No. 610,2`33

7 Claims. (Cl. 60-97) This invention relates to improvements in fluid actuated power units for operating devices in which a relatively long movement necessitating a low pressure is rst required followed by a short movement at a higher pressure.

A known form of runit for such purpose consists of a single cylinder having the requiredivolume to give the large movement while the pressure of the fluid is relatively low, the pressure of the fluid then being increased to give the required high pressure. In such case if the iluid is elastic such as air, this necessitates the relatively large volume of the cylinder being charged with air at high pressure which is not economical since the uid used is the same as that required to move the piston through the whole distance at high pressure.

To overcome this uneconomical use of lluids under pressure, power units have been proposed making use of two cylinders, one of relatively large capacity to effect the first movement under low pressure and the other of relatively small capacity to apply the iinal pressure.

According to the present invention two pairs of cylinders are provided, one pair comprising a cylinder to which air is supplied at relatively low pressure to cause the piston therein to move through a relatively long distance and the second cylinder containing a uid (usually oil). The pistons of these two cylinders are so mechanically coupled that they move in sympathy with one another and can be in tandem. The oil in the second cylinder is in a closed circuit connecting the two ends of the oil cylinder and including a reservoir and expansion chamber which permits the oil in the oil cylinder to be transmitted from one side of its piston to the other when this piston is moved in sympathy with the piston in the air cylinder.

The second pair of cylinders comprise an air cylinder of relatively large diameter and short stroke, and an cil cylinder of smaller diameter, the pistons of these pair lof cylinders being preferably connected in tandem. Air pressure applied to one side of the piston in the air cylinder causes movement to the piston in the oil cylinder. The movement of this piston in the oil cylinder iirst interrupts the circuit connecting the two ends of the oil cylinder of the rst pair of cylinders and further movement intensities the oil pressure acting on one side of the piston in the first cylinder and the oil cylinder, in the second pair of cylinders. At the end of the pressing operation the oil pressure is relieved in the oil cylinder of the rst pair of cylinders by admitting air pressure to the opposite side of the piston in the air cylinder of the second pair and so retracting the piston of its associated oil cylinder and to reopen the circuit connecting the two ends of the iirst oil cylinder, so that when air pressure is admitted to its associated air cylinder to reopen the Y press, the oil is transferred from one side of the piston in the oil cylinder to the other side.

The invention is particularly applicable for the operating of pressing machines including presses of the type used in laundry, dry-cleaning and clothing establishments.

When the unit is appliedrto a press having an upper pressing surface or head carried on a lever which pivots about a Xed fulcrum and it is desired that the movement of the head should be through a large angle to a position adjacent to the lower pressing surface or buck and then to apply considerable pressure between the head and the buck, the air cylinder of the first pair of cylinders is iirst operated to bring the pressing head into a position adjacent to the buck and the inal pressure applied to the article on the buck by the operation of the second air cylinder. Y

The invention is lillustrated in and will be described with reference to the accompanying drawings, in which:

Fig. 1 is a sectional elevation of the power unit,

Fig. 2 is an end elevation thereof in direction of arrow 2 Fig. l,

l Fig. 3 is a perspective view showing the power unit tted to a pressing 'machine of the type having a stationary lower surface to receive the work and an upper moveable pressing surface or head carried on a lever which pivots about a iixed fulcrum, suitable control mechanism being also shown,

Fig. 4 is a diagram of the connections and pipes of the control mechanism shown in Fig. 3, I

Fig. 5 is a vertical section of a four-way distribution valve employed with the control mechanism, the sliding member of the valve being in its lower position, and

Fig. 6 is a similar section of the valve with the sliding member in its upper position.

Referring to Figs. l and 2, an air cylinder A and an oil cylinder B are disposed vertically, or substantially so, one above the other. The piston a1 in the air cylinder A and the piston b1 in the oil cylinder B are secured to a common rod a2 and consequently these pistons move in their respective cylinders in sympathy with one another. A cylinder cover b2 common to the air cylinder A and the oil cylinder B is disposed between the two cylinders. The' cover b2 is fitted with suitable packing means a3 and b3 to prevent air passing from the air cylinder A t0 the oil cylinder B, or conversely oil from the cylinder B to the cylinder A. A vent hole a4 is drilled in the cover b2 and in the sleeve on casting C to enable any leakage which might take place to be detected.

At the top of the cylinder A is fitted a cover a5 provided with a suitable gland packing a6 through which the piston rod a2 passes. To the upper end of the piston rod a2 is secured a crosshead a7 or other tting suitable to couple to the part of the machine to be actuated.

yAt the bottom of the oil cylinder B is a cover D in which a circular hole d1 is formed to provide pivotal means to secure the assembly to the rigid frame of the machine. Recesses c1 and` c2 are formed in the casting or sleeve C to receive the adjacent ends of the cylinders A and B in the cover D; a recess d2 is formed to receive the lower end of oil cylinder B. O rings E or other suitable packing means are provided between the cylinder B and the walls of the recess to prevent leakage of oil.

The cylinders A and B are rigidly secured together and in the recesses of the sleeve C and cover D by means of the clamping screws F.

Two further cylinders, an air cylinder G and an oil cylinder H, are arranged at one side of the cylinders AA and B. The piston g1 in the cylinder G is secured to a rod g2 which is extended to enter thecylinder H at g3 to form a piston or ram therein so that the two pistons move in sympathy with one another. The cylinders G and H are shown parallel to the common axis of the cylinders A and B and in the working position the axis is substantially vertical but it is to be understood that the position of the cylinders G and H is not restricted to that shown in the figures but that the common axis of these cylinders may be disposed at right angles or other convenient angle to the axis of the cylinders A and B. Similarly the axis of cylinders A and B is not restricted to a substantially vertical position.

A common cover g4 is arranged between the cylinders G and H provided with suitable packing means g5 to prevent leakage between the two cylinders. An oil vessel .T is provided to form a breathing chamber and to allow for expansion of the oil in the cylinder H. The vessel I is shown in Figs. l, 2 and 3 attached to the cover g'7 of the cylinder G but if more convenient it may be independent thereof. The cover i1 of the vessel I is provided with a vent i2.

Ports K and K1 are provided between cylinders B and H to allow the oil in cylinder B to move freely from one side of piston b1 to the other side while the piston g3 is in the out position shown in Fig. l. As the piston g3 moves towards the in position, the port k1 is closed by the rod g2 and oil above the piston b1 can be displaced freely in to the vessel I through the port K and the pipe connection f.-

In the arrangement shown in the figures the pair of cylinders A and B and the pair of cylinders G and H are securedV in their relative positions by the members D and C which form respectively the cover of the cylinder B and the sleeve to which the adjacent ends of the cylinder A andvB are secured. The bottom of the cylinder H is connected to the bottom of the cylinder B by a passage K1 in the member D. The unit may be drained also throughthis passage K1 by extending it as shown to the side of they member and providing a T fitting M at the outer end of the passage, the T fitting having a controlled outlet at m1 and means m2 for attaching a pressure gauge thereto.

In'such arrangement it is convenient to formthe ports K and k1 in these members. If it is desired to dispose thepairs of cylinders to other relative positions more suitable toa particular application, the ports K and k1 mayibereplaced by pipe connections. Y

lThe unit 4can be charged with oil through the vessel .l to a convenient free surface level i4.

A controllediair supply is connected through the pipes a1 to the cylinder A at as below the piston a1 and at a9 above the piston a1. The air supply is also connected to the cylinder G at g8 above the pistou g1 and at g9 below the piston g1.

To operate the unit, air under pressure isadmitted to cylinder A at a8 below the piston a1 thereby causing the piston rod a2 to move outwardly carrying with it the attached crosshead a". The crosshead al being connected to the movable member by suitable mechanical means causes the latter to move through a relatively long distance to a position adjacent to a stationary member. During the time that the piston a1 is traversing outwardly the piston b1 in cylinder B is moving in sympathy and oil is transferred from above piston b1 to below it by way of the port K, the cylinder H and the passage K1.

Air under pressure can then by means of a suitable control be admitted to the cylinder G at g8 above the piston g1 thereby causing the piston g1 to traverse cylinder G in direction towards cylinder H. As the rod g2 moves in sympathy with the piston g1 it irst closes the port k1 thus causing the oil in the cylinder H to be subjected to pressure, which pressure is transmitted to the cylinder B below the piston b1, throughthe passage K1. The oil thus displaced from the cylinder H to the cylinder 4 B moves the piston b1 and as the latter is rigidly connected to the crosshead a7 this motion is transmitted to the mov# able member through the aforesaid mechanical means supply to the cylinder G through connection g8.

connecting the crosshead to the member. The movable member having been arrested adjacent to the lixed member, as previously described, the movement given to the piston b1 by oil transferred from cylinder H to cylinder B will cause the movable member to be brought into inti mate contact with the stationary member and will then exert a pressure between the members comparable with the pressure acting on the'piston b1.

The pressure in the cylinder B is higher than the pressure of the air supplied to cylinder G in the ratio of the area of the piston g1 to the area of the piston g3.

It will be understood from the foregoing description that the long movement of the movable member necessary to bring it adjacent to the stationary member is obtained by using air` at relatively low pressure and the final pressure between the members is increased by the intensifying action of the difference in diameters of the pistons g1 and g3. The pressure between the members may be controlled by controlling the pressure of the air One method of controlling the air pressure to cylinder G is by means of a reducing valve with means of readily adjusting the pressure in the supply to the connection g8.

To retract the movable member from the stationary member air is admitted to the cylinder G through the connection g9 to the underside of the piston g1, causing it to move in a direction away from cylinder H. As the piston g3 moves in sympathy with the piston g1 it will rst relieve the pressure acting on piston b1 and then uncoverthe port k1, leaving a clear passage for oil to be transferred from below to above the pistonb1 through the ports K and k1. Air can then be admitted to the cylinder A through the connection a9 above the piston al causing the piston a1 to move inwardly, and acting through rod a24 andcrosshead a" to cause the movable member to ing a cover n1 at the lower end which is secured to themember D whereby the cylinder N is held rigidly in relation to the cylinders A and B. The upper end of ythe cylinder N is closed by a cover n2 held in position by a screwed socket n3 which is extended upwards to carry an oil chamber n4 .which serves as a breathing chamber and is closed by the cover 115. A rod n6 extends downwards through the chamber n4 into the cylinder N and carries at its lower end a piston n". The

' upper end of the rod 116 is secured to the crosshead al which operates the movable member. A cylinder n.8 is formed in the cover n1 to receive a circular extension n? of the piston 117 when the latter is at the lower end of its stroke. A cylinder n10 is also formed in the piston n?. The cover n? has a cylindrical extension rz-11 which enters cylinder n10 of the piston n'7 `when the piston is atA the upper end of its stroke. Suitably sized vent holes 1112 are drilled in piston n'l. The cylinder N is charged with a iluid suitable to perform the action of snubbing to some free surface level in the chamber n4;

As the lower end of the cylinder N is scoured relative to the lower ends of the cylinders A and B of the power unit and the rod ns is secured to the crosshead a7 then piston nl will move in sympathy with the pistons a1 and b1 of the power unit. In operation, as the piston n'l moves in a downward direction fluid is displaced freely from the underside of piston n" to the upper side thereof through the annular space 1114 between the piston n'l and the inside of the cylinder N. As the piston nl approaches the end of its downwardstroke the extension 119 of the piston n'I enters the bored portion n? of the cover nl and traps fluid therein.l 'As the extension 119, travels further into the bored portion 118 the fluid is brought under pressure which reacts against the moving parts to bring them to rest. In order that the moving parts may be brought to rest smoothly the sizes of the vent holes 1112 are suitably graduated to slow down the rate of escape of fluid from the cylinder 118. When the piston 11'7 moves in an upward direction the extension 1111 of the cover n2 Iwill enter the cylindrically bored portion 1110 of piston 11'I and the movement of the parts will be gradually arrested in a similar manner.

It is to be understood that the form of snubber employed is not restricted to that described and shown in Fig. 1. Although experience has shown that there are certain advantages to be obtained by tting an independent snubbing device, which allows a wider choice of fluid suitable for that purpose, the arrangement described might be incorporated in the air or the oil cylinders of the power unit by making either the piston in the air cylinder or the piston in the oil cylinder similar to the piston 117 and fitting covers similar to covers 111 and 112 to the appropriate cylinder.

Referring now to Fig. 3 pressure air is connected to the pressing machine `at O and is conveyed to a reducing valve R by the pipe p1 and by branches p2 and p3 from the pipe p1 to the valves P and Q. The valve P is controlled by a push button p4 and when this button is depressed air is allowed to pass through the valve P from the pipe p2 to the pipe p5 thus conveying pressure to the top of the air ram S causing the ram s1 to descend and contact an adjustable screw s2 attached to a lever s3. The lever s3 is thus moved in a downward direction and by its connection to a rod T by a screw s4 the end t1 of the rod T is caused to move downwards and operate a lever q1 of a rotary valve Q which may be of the same construction and operation as described in the specification of our application 6,237/ 5l.

The operation of the lever q1 causes the rotary member of the valve Q to uncover ports in the valve body to allow pressure-air to pass through the valve Q from the pipe p3 to the pipes u6 and p8 and air in the pipe p9 to pass through the valve Q to atmosphere through the pipe p10. Depression of the button p4 of the valve P thus causes pressure-air to be supplied through the pipe p6 and connection a8 to the cylinder A to the under side of the piston al and connects the cylinder A above the piston a1 to atmosphere through the connection a9 and pipes p9 and p10. The piston a1 under the influence of the pressure air moves in an upward direction and being connected to the lever U of the pressing machine through the rod a2 and crosshead a7 causes the lever U to turn about its fixed fulcrum ul thereby bringing the movable pressing surfaces 112 of the pressing machine to a position adjacent to the fixed pressing surface 113 thereof.

The end r2 of the rod T is connected to the lever U by the link t3 so that the end t2 will move upwards in sympathy with the movement of the lever U and since the other end 1l of the rod T is held in position by the ram S, the upward movement of the end t2 of the rod T causes the valve Q to be restored to its neutral position and when the valve Q is in the neutral position pressure air is cut ol from both ends of cylinder A and both ends are connected to atmosphere through the pipes p6, p9 and p10.

The top of a valve W, the construction of which will be described later is connected to the pipe p6 through a pipe p8 so that the pressure of the air at the top of the valve W is always the same as that in the pipe p6, that is, while pressure air is moving the piston 11 in the cylinder A in an Iupward direction, pressure air is acting on the top of the valve W and when the piston a1 cornes to rest due to the 'valve Q being restored to its neutral position the pressure at the top of valve W 'will be that of the atmosphere.

When the push button p1 of the valve P is in its nor-Y 7.5. W and fherire ,12F t0 the tvp 0f the Pistes al ia the. ,ola

mal position pressure air is shut olf P, and the pressure of air in the pipe p5 is atmospheric. When the push button p4 is depressed pressure air passes through the Valve P to the pipe p5 and so to the pipe 'p7 which is connected to valve V on the lever U. When the valve V is in its normal position connection between the pipes p'I and p11 is closed, but when an operating lever v1 is depressed, the valve is opened to connect the pipes pI with the pipe p11. The pipe p11 connects the valve V with the bottomV of the valve The construction of the valve W is shown in detail in Figs. 5 and 6. The valve is shown in its normal position in Fig. 5 with the sliding member thereof held in its lowerposition by a spring W2. The strength of the spring W2 while being sufficient to maintain the sliding member in its lower position, normally, is not sufficient alone to resist upward movement of the sliding member w1 against pressure air admitted to the underside of the valve through pipe p11.

Air at a pressure controlled by the setting of reducing valve R is supplied to the valve W by a pipe p12 and a pipe p14 is connected to the cylinder G at g9 below piston g1, consequently air pressure is transmitted through valve W from the pipe'pl2 to the pipe p14 to the underside of piston g1 to hold the end g3 of the ram g2 normally clear of port k1.

The operation of the pressing machine will now be described with reference' to the function of the several valves and also to certain features of the arrangement which are conducive to the safety of the operator.

It has already been described how the pressing surfaces 112 and 113 can be brought adjacent to one another by depressing the button p4 of the valve P- and that as the pressing surfaces assume this position the valve Q is restored to its neutral position by the link t3 and leverr T.-

With the Ivalve Q in the neutral position the air on both sides of the piston a1 in cylinder A is at atmospheric pressure, consequently no pressure is exerted between the pressing surfaces u2 and 113. If the manual pressure on the button p4 is now released the rod T and the valve Q by the reaction of rod T on lever q1 are restored to normal positions by the spring t5 with the pressing machinev in the open position.

As already described when the button p4 of the'valve P is in its free or normal position pressure-air is cut olf from pipes p5 and p7, and consequently from valve V, the valve V therefore being inoperative unless the button p4 is depressed.

Since the valve V must be manually operated to bring the surfaces u2 and 113 into pressure contact, the operator must employ Iboth hands, one to operate the valve P and the other to operate the valve V before pressure can be applied between the pressing surfaces.

Further, when the button p4 of the valve P is depressed to bring the pressing surfaces u2 and 113 adjacent to one another by admitting pressure `air to the pipe p6 through the valve Q, pressure air is also admitted through the pipe p8 into the top w3 of the valve W (see Fig. 5),A

this pressure assisted by the spring W2 maintains the sliding member w1 in its lower position. If under these conditions the valve V is opened to admit pressure air through the pipe p11 to the underside w4 of the valve W the sliding member w1 still remains in its lower position due to the additional force of the spring W2 acting downwards `and the lower position of the member w1 will be maintained until the air pressure at the top` W2 is reduced. Pressure at the top of the valve W will be reduced when the pressing surfaces have been brought adjacent to one another and the valve Q has assumed its normal position as the pressure air at the top w2 will then exhaust to atmosphere through pipe p8, valve Q and pipe p10. The sliding member w1 of the valve W will be moved -to its upper position by the pressure air at w4 and pressure air from the pipe p12 will pass through the valve 7 der G, causing the piston g1 to move downwards Aand the ram g3 to close the port k1 and subject the oil in the cylinder H to pressure which pressure is transmitted to the underside ofthe piston bl in the cylinder B causing the pressing surface u2 to be brought into pressure contact with the surface n3. l l

From the above it Iwill be seen that the Vpressure cannot be applied at the pressing surface until the surfaces have rst been brought adjacent to one another. This condition is further conducive to the safety to the operator and the more satisfactory operatingrof the pressing machine. Y v

If the lever v1 -is now released the valve V returns to its normally closed position, trapping pressure air in the pipe p11 and below the moving part w1 of the valve W. If pressure is then released on the push button p4 the end r1 ofthe rod T will be returned to its normal position for the pressing machine in its open position and the end W2 of the valve W 'will still be open to atmosphere through the pipe p8 and the valve Q and pressure air will be acting on the upper Vside of the piston a1 in the cylinder A through the valve Q and pipe p9. Pressure air above the piston a1, however, can not move the piston a1 in a downward direction due to the intensified oil pressure below the piston b1 in the cylinder B, which pressure is maintained due to the air pressure acting on vthe upper side of the piston g1 in the cylinder G. Y

To open the press the valve V is opened by depressing the lever v1 and pressure air trapped in the pipe p11 and at the bottom w4 of the valve W will escape to atmosphere through the valve P. The sliding member w1 of the valve W will then be restored to its normal lower position (Fig. by the spring W2. The pipe p13 is thus opened to exhaust through the valve W to the pipe p16 and the pressure air pipe p12 through the valve W and pipe p14 to the under side of the piston g1 in the cylinder G. As pistong1 is thus moved upwards oil pressure is released under the piston b1 and the port k1 is uncovered. Pressure air above the piston a1 Will move the piston downwards, thus opening the pressing machine and the valve Q by the action of the rod T, link t3 and lever q1 is restored to its normal position.

We claim:

l. A fluid actuated power unit for operating a device in which a long movement requiring a relatively low pressure is iirst required to bring two members adjacent to one another but not in pressure contact, followed by a short movement necessitating a higher pressure to bring them into pressure contact, comprising a pair of cylinders in tandem, one cylinder being adapted to be connected to a source of fluid pressure and the other being adapted to contain a liquid, a piston in each cylinder, a common pisv ton rod on which the pistons are mounted, the said piston rod being adapted to be connected to the member to be operated, a second pair of cylinders also in tandem, one cylinder being adapted to be connected to a source of fluid pressure and the other containing a liquid, a piston in each cylinder, a common piston rod on which the pistons are mounted, the 'area of the piston in the cylinder of said second pair connected to the source of lluid pressure being .greater than the area of the piston in the associated 'liquid containing cylinder, a conduit between the liquid containing cylinders of the two pairs, means for admitting iluid under pressure to the fluid pressure cylinder of the vrst pair to give the long movement at a low pressure, and means for subsequently admitting iluid pressure to the iiuid pressure cylinder of the second pair to cause the piston thereof to move and apply pressure to the liquid in its yassociated liquid cylinder, such liquid under pressure being Vtransmitted through said conduit to the liquid containing cylinder of the rst pair to act on the piston thereof and exert an increased pressure on' the common piston rod, thereby giving a small movement of the latter at a higher pressure. K

2. -A uid actuated power unit as in claim l Acomprising means for admitting fluid under pressure to the op# posite side of the piston in the duid pressure cylinder of the second pair to move the latter in the reverse direction, thereby relieving the pressure in the liquid containing cylinder of the second pair and consequently in the liquid containing cylinder of the first pair and also to the piston in the lluid pressure cylinder of the first pair to return it and lthe member connected thereto to its inoperative position so that the unit is double acting.

3. A lluid operated power unit as in claim 2 in combination with said member to be operated and separate means connected to said member for dampening the return stroke of said unit.

4. A fluid actuated power unit for operating ldevices in which a long movement requiring a relatively low pressure is first required to bring two members adjacent to one another but not in pressure contact, followed by a short movement necessitating a higher pressure to bring them into pressure contact comprising a pair of cylinders in tandem, one cylinder being adapted to be connected to a source of fluid pressure and the other being adapted to contain a liquid, a piston in each cylinder, a common piston rod on which the pistons are mounted, the said piston rod being adapted to be connected to the member to be operated, va second pair of cylinders also in tandem, one cylinder being adapted to be connected to a source of tiuid pressure and the other containing a liquid, a piston in ea'ch cylinder, a common piston rod on which the pistons are mounted, the area of the piston in the cylinder of said second pair connected to the source of iluid pressure being greater than the area of the piston in the associated liquid containing cylinder, and a conduit between the liquid cylinders of the two pairs, means for admitting fluid under pressure to the liuid pressure cylinder of the first pair to give the long movement at a low pressure, means for admitting iluid under pressure to the iluid pressure cylinder of the second pair to cause the piston thereof to move and apply pressure to the liquid in the associated liquid containing cylinder, this pressure being transmitted through the conduit to the liquid in the liquid containing 'cylinder of the first pair to act on the piston thereof and exert'an increased pressure on the common piston rod, thereby giving a small movement of the latter at a higher pressure, a further cylinder, a pistou therein, ya third piston rod on which the piston is mounted, means for connecting said third piston rod to the piston rod of the iirst pair of cylinders, the further cylinder containing a suitable uid and the piston being a loose t inthe cylinder so that fluid may readily pass from one side thereof to the other during the greater part of its stroke, an extension ori the piston in the further cylinder which extension, has a close fit in the end of the bore of the cylinder so that during the final movement of the piston in the further cylinder fluid will tend to be compressed in said end of the cylinder, and means forming a series of passages through the piston in the further cylinder which will allow the gradual passage of the uid from one side of said piston to the other during this unal movement, these passages being so arranged that the passage of the iluid is progressively decreased as said piston yapproaches the end of its stroke.

5. In combination with the power unit defined in claim 1 and wherein said device is a pressing machine of the type used in laundry and wherein one of said members is stationary and the other member is movable and is connected to the piston rod of the first pair of cylinders, valve means controlling the admission of iluid under pressure to the fluid pressure cylinder of said first pair of cylinders and subsequently to the iiuid pressure cylinder of said second pair of cylinders, and manual means for actuating said 'valve means.

6. In the combination defined in claim 5, said valve means lcomprising a rst manually operable valve for controlling the admission of uid under pressure to the fluid pressure cylinder lof said rst pair of cylinders to effect said long movement of said movable member of the device to a position adjacent said other member, a second manually operable valve, and means operable when said rst and second val'ves are actuated at the same Itime for admitting uid under pressure to the fluid pres- '5 Asure cylinder of the second pair of cylinders.

7. In the combination defined in claim 6, means pro- 'viding a connection from said movable member to said -valve means for cutting o the application of fluid pressure to the pressure cylinder of said first pair of cylinders 10 at the end of said long movement of the movable member` References Cited in the le of this patent UNITED STATES PATENTS 

